/Engine/Plugins/Online/OnlineServices/Source/OnlineServicesInterface/Public/Online/Sessions.h
This event will trigger as a result of leaving or destroying a session.
[TOnlineEvent](API\Plugins\OnlineServicesInterface\Online\TOnlineEvent)< void(const [FSessionLeft](API\Plugins\OnlineServicesInterface\Online\FSessionLeft) &)> OnSessionLeft()